9 reds in a row: the odds — both of them

Two different questions hide in this query. A specific window: the next 9 spins all red = (18/37)⁹ = 0.153% (1 in 655). Your actual session: the chance of seeing a run of 9+ reds at least once is 7.1% in 100 spins, 14.1% in 200, 54.3% in 1,000 — computed exactly with a Markov chain (method), a figure most sites never touch.⚙ computed

Will you see it? Session odds

Session length	P(streak ≥ 9 at least once)	Expected count of such runs
50 spins	3.33%	0.03
100 spins	7.07%	0.07
200 spins	14.13%	0.15
500 spins	32.24%	0.39
1000 spins	54.35%	0.78

Nine happens somewhere on a twenty-table floor most nights — personal encounters are occasional, floor-wide they’re furniture.

Why this streak matters: it’s a Martingale killer

Betting black through 9 reds on a $5 Martingale means your next bet is $2,560 — already past a typical $500 table max, so the system is dead before it can “recover”. Our million-session Martingale run shows exactly how often these walls arrive.

The fallacy checkpoint

After 9 reds, the next spin is still red with probability 18/37 = 48.65%. The wheel has no memory — streaks are what independence looks like, not evidence against it. The 1913 Monte Carlo table famously ran 26 blacks while the room bet ever-heavier on red; the episode named the gambler’s fallacy — its place in the game’s full timeline here.

Other streak lengths

3 in a row 4 in a row 5 in a row 6 in a row 7 in a row 8 in a row odds hub →

Frequently asked

What are the odds of 9 reds in a row in roulette?

For a fixed window: (18/37)^9 ≈ 0.153% on a European wheel, about 1 in 655. On American wheels it’s rarer: (18/38)^9 ≈ 0.120%.

Will I ever see 9 reds in a row?

More often than intuition says: at least once in 14% of 200-spin sessions by exact Markov computation. Long streaks are a normal feature of independent spins.

After 9 reds, is black due?

No — each spin is independent, so black is still 48.65% (EU). Betting bigger on “due” colors is the gambler’s fallacy, and it’s exactly how streaks eat Martingale bankrolls.